The proposed research will amplify previous studies of enzymes involved in the metabolism of ornithine and glutamate in rat tissues during normal development. Experiments will test the way in which hormones promote functional differentiation by inducting or suppressing enzyme synthesis in different organs. An inbred strain with frequent mortality of the young and hormonally pretreated neonatal rats of another strain will be used as animal models to study aspect of the Sudden Infant Death Syndrome. BIBLIOGRAPHIC REFERENCES: Herzfeld, A. and Raper, S.M.: Amino acid metabolizing enzymes in submaxillary gland and pancreas. Enzyme, 1976. (In press). Herzfeld, A. and Raper, S.M.: The heterogeneity of arginases in rat tissues. Biochem. J. 153:469-478, 1976.